freebsd stable - Mar 2014 - device ada n/ in kernconf, how to omitt for hv_storvsc.ko

Hello,

I'm experimenting with MS-Hyper-V and saw that as soon as hv_storvsc.ko
is loaded, an IDE hdd attaches as 'da' _and_ 'ada' (the former
seems to
be called ?FastIDE? on ?synthetic storage driver? and gains efficiency
for HDD workloads).

There's the hv_pci_ata_disengage.ko pseudo driver, but that also makes
IDE cdrom unavailable ? same as disabling ata/atapci! Can't really get
the idea of that module?

I'd prefere to disable 'ada' only (leaving cdrom via
atapci->ATA_CAM->cd).
But I can't find the place where ?device ada? gets defined for kernel
conf. ?device ata? is in GENERIC, along with da, sa, scbus etc., but no
'ada' ?!?. No trace of 'ada' in DEFAULTS either!?!

Is there something like hint.ada.disable=1 ?
Can I use ?nodevice ada? to exclude it from my custom kernel?

Thanks,

-Harry

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> Hello,
>
> I'm experimenting with MS-Hyper-V and saw that as soon as hv_storvsc.ko
> is loaded, an IDE hdd attaches as 'da' _and_ 'ada' (the
former seems to
> be called ?FastIDE? on ?synthetic storage driver? and gains efficiency
> for HDD workloads).
>
> There's the hv_pci_ata_disengage.ko pseudo driver, but that also makes
> IDE cdrom unavailable ? same as disabling ata/atapci! Can't really get
> the idea of that module?
>
> I'd prefere to disable 'ada' only (leaving cdrom via
atapci->ATA_CAM->cd).
> But I can't find the place where ?device ada? gets defined for kernel
> conf. ?device ata? is in GENERIC, along with da, sa, scbus etc., but no
> 'ada' ?!?. No trace of 'ada' in DEFAULTS either!?!
Greetings,
 Off the top of my head, I /believe/ it's (ada) a part of the ahci
implementation.

--Chris
>
> Is there something like hint.ada.disable=1 ?
> Can I use ?nodevice ada? to exclude it from my custom kernel?
>
> Thanks,
>
> -Harry
>
>

Quoth "Chris H" <bsd-lists at
bsdforge.com>:
> >
> > I'm experimenting with MS-Hyper-V and saw that as soon as
hv_storvsc.ko
> > is loaded, an IDE hdd attaches as 'da' _and_ 'ada'
(the former seems to
> > be called ?FastIDE? on ?synthetic storage driver? and gains efficiency
> > for HDD workloads).
Is this a problem? Can't you just ignore the one you don't want to use?

If nothing else, you could hide the device node using devfs.rules.
> > I'd prefere to disable 'ada' only (leaving cdrom via
atapci->ATA_CAM->cd).
> > But I can't find the place where ?device ada? gets defined for
kernel
> > conf. ?device ata? is in GENERIC, along with da, sa, scbus etc., but
no
> > 'ada' ?!?. No trace of 'ada' in DEFAULTS either!?!
>
>  Off the top of my head, I /believe/ it's (ada) a part of the ahci
> implementation.
No, it works perfectly well without ahci (I'm using it with ataintel,
since the ICH7 in this box doesn't support AHCI).

It's compiled in with this line in sys/conf/files:

    cam/ata/ata_da.c                optional ada | da

which says 'include this file if either of "device ada" or
"device da"
were requested'. So, I believe that if you want 'device da', you get
'device ada' as well, unless you edit that line to remove the '|
da' and
make buildkernel. (I make no guarantee that this won't break things. I'm
not a kernel hacker.)

Ben